Anti-vibration support for construction machine cab

ABSTRACT

A construction machine adapted to suppress transmission of vibrations from a main frame to a cab. The cab is supported on a bed frame by anti-vibrational mounts, each provided with a laminated rubber body having relatively high rigidity against vibrations in vertical directions and relatively small rigidity against vibrations in horizontal directions. A floor panel of the cab is connected to the bed frame by horizontally mounted oil dampers constituting vibration attenuators. Consequently, when the bed frame is vibrated, the cab undergoes horizontal parallel movements due to flexure of the laminated rubber bodies, thereby preventing occurrences of pitching, rolling and yawing vibrations. Even if residual vibrations occur on the cab due to the resilient restoring force of the laminated rubber bodies, such residual vibrations can be attenuated by the oil dampers, thereby preventing the phenomenon of resonance which might otherwise result from the residual vibrations and to improve the amenity within the cab.

TECHNICAL FIELD

This invention relates generally to a construction machine with anoperator's cab, for example, a hydraulic excavator, a hydraulic craneand the like, and more particularly to a construction machine which hasan operator's cab supported on a frame of the machine in a vibrationdamped state.

BACKGROUND ART

Generally, a hydraulic excavator as a construction machine with anoperator's cab is largely constituted by a truck body, a rotary upperbody which is rotatably mounted on the truck body, and a workingmechanism which is provided on the upper rotary body for upward anddownward lifting movements. Provided on a frame of the upper rotary bodyis an operator's cab which accommodates control instruments and devicesto be manipulated by an operator in controlling operations of the truckbody and working mechanism, and an operator's seat to be occupied by anoperator.

In connection with hydraulic excavators as mentioned above, forinstance, Japanese Laid-Open Patent Publication No. H5-125745 disclosesa hydraulic excavator having an operator's cab mounted on a supportframe in a vibration damped state, by the use of anti-vibrational mountsin the form of liquid-sealed rubber mounts which are interposed in fourcorner portions between the support frame and the operator's cab in anattempt to suppress transmission of vibrations from the frame to the cabduring a ground excavating operation or when the machine is in travel.

In the case of the prior art hydraulic excavator with the arrangementsjust mentioned, vibrations which occur to the support frame during atraveling or excavating operation, are absorbed by vertical flexures ofthe anti-vibrational mounts to prevent direct transmission of thevibrations to the operator's cab. This contributes to improve theamenity of the operator's cab as well as the maneuverability of variouscontrol levers and the like.

Among hydraulic excavators of various classes, the large-size hydraulicexcavators which are used, for example, in excavating a large quantityof earth at open mining sites, are usually constructed in a differentconcept. Namely, in the construction of large-size hydraulic excavators,there has been a trend toward giving top priority to the machinedurability rather than the amenity of the operator's cab because, in thecase of machine trouble, repair work could take an enormously long time.For this reason, usually little attention is paid to the amenity of theoperator's cab in the construction of large-size hydraulic excavators.

Especially in the case of a hydraulic excavator of the so-called highmount cab type, a vertical or upright bed frame is provided on a mainframe which constitutes a bottom portion of a rotary body, and anoperator's cab is mounted on top of the bed frame. In a high mount cabtype hydraulic excavator, due to the provision of the bed frame, theoperator's cab is located in a position which is largely spaced awayfrom a truck body in an upward direction, and vibrations which occurwhen the machine is in travel or which occur during an excavatingoperation are transmitted to the cab through the bed frame, therebyputting the cab in conspicuous vibrational movements.

In this regard, even for large-size hydraulic excavators, it isconceivable to employ the above-mentioned anti-vibrational mountsbetween a bed frame and a cab structure to suppress transmission ofvibrations from the bed frame to the cab and to improve the amenity ofthe cab in a similar manner.

However, large-size hydraulic excavators which are often used for ahorizontal excavating operation by a loader bucket, have an inherentproblem that vibrations in back and forth directions as well asvibrations in lateral directions (both vibrations hereinafter referredto collectively as “horizontal vibrations” for brevity) are more likelyto be transmitted to the cab during excavating operations. Nonetheless,the prior art anti-vibrational mounts which are designed to absorbmainly vertical vibrations, are arranged to have relatively low rigidityagainst vertical vibrations and relatively high rigidity againsthorizontal vibrations.

Therefore, in the case of high mount cab type hydraulic excavators, theconventional anti-vibrational mounts which have high rigidity againsthorizontal vibrations, are incapable of absorbing horizontal vibrationswhich occur to a bed frame at the time of ground excavating operations.Accordingly, as shown in FIG. 17, if a bed frame 101 is put invibrations in a back and forth direction (in the direction of arrow a),a cab 102 is largely shaken on the bed frame 101 by pitching (back andforth vibrations) as indicated by arrow b to deteriorate the amenity ofthe cab as well as the maneuverability of control levers or otherdevices to a considerable degree. On the other hand, if the bed frame isput in vibrations in a lateral direction, the cab 102 is also largelyshaken by rolling (rightward and leftward vibrations). A further problemis that, when the rotary body is put in a rotational movement, the cab102 is shaken by yawing (vibrations in a rotational direction).

DISCLOSURE OF THE INVENTION

In view of the problems with the prior art as mentioned above, it is anobject of the present invention to provide a construction machine withan operator's cab on a frame, which is arranged to suppress transmissionof vibrations from the frame to the cab.

In accordance with the present invention, the above-mentioned problemsare solved by the provision of a cab support which is applicable to aconstruction machine with an operator's cab, basically including asupport frame, an operator's cab mounted on the support frame andinternally defining an operating room, and four anti-vibrational mountsinterposed in four corner portions between the support frame and the caband adapted to support the cab in such a manner as to suppresstransmission of vibrations from the frame to the cab.

More particularly, according to the present invention, there is provideda construction machine with an operator's cab, which is characterized bythe provision of: four anti-vibrational mounts each constituted by alaminated rubber body having relatively high rigidity against vibrationin a vertical direction and relatively low rigidity against vibration ina horizontal direction; and four vibration attenuating devices locatedin four corner portions between the frame and cab and in cooperativepositions relative to the anti-vibrational mounts to attenuatehorizontal vibrations transmitted to the cab.

With the arrangements just described, when the frame is put in vibrationin a lateral direction, the laminated rubber bodies of the respectiveanti-vibrational mounts are caused to flex largely in a horizontaldirection, thereby suppressing transmission of vibration from the frameto the cab. At this time, even if the vibration of the frame istransmitted, the cab is simply put in horizontal parallel movements andprevented from being shaken largely by pitching or rolling vibrationsbecause the laminated rubber bodies of the anti-vibrational mounts havehigh rigidity against vibrations in vertical directions. Besides, evenif horizontal residual vibrations occur to the cab due to resilientrestoring forces of the laminated rubber bodies which are flexed byvibrations of the frame, such residual vibrations can be damped by therespective vibration attenuating devices.

In this instance, according to the present invention, two of thevibration attenuating devices, which are located in front portions ofthe cab, are mounted in a horizontal plane and in an angular posturesuch that respective longitudinal axes are intersected with each otheron the front side of the cab, while the remaining two vibrationattenuating devices, which are located in rear portions of the cab, arelikewise mounted in a horizontal plane and in an angular posture suchthat respective longitudinal axis are intersected with each other on therear side of the cab.

Further, each one of the vibration attenuating devices according to thepresent invention is so arranged as to have a longitudinal axis thereoflocated in a circumscribing position relative to an imaginary ellipsedrawn around a bottom center portion of the cab.

With the arrangements just described, the respective vibrationattenuating devices are mounted in a horizontal plane and in an angularposture which is inclined relative to back and forth and transversedirections of the cab. Therefore, when the cab is put in vibrations inback and forth directions or in lateral directions, these vibrations canbe effectively damped by the vibrations attenuating devices. Further,the vibration attenuating devices also function to effectively suppressyawing movements which may occur to the cab as a result of a rotationalmovement.

Further, in one particular form of the present invention, the frame is amain frame constituting a bottom portion of a rotary body of themachine, and the cab is supported on the main frame through theanti-vibrational mounts.

In this instance, when the frame is vibrated during a vehiculartraveling operation or a ground excavating operation of the machine,transmission of the vibration of the frame to the cab can be suppressedby the respective anti-vibrational mounts.

Further, in another form of the present invention, the frame is composedof a main frame constituting a bottom portion of a rotary body of themachine and a bed frame standing vertically on the main frame, and thecab is supported on the bed frame through the anti-vibrational mounts.

In this instance, the respective anti-vibrational mounts function tosuppress transmission of vibrations from the frame to the cab throughthe bed frame, thereby preventing the cab from being largely shaken onthe bed frame.

Furthermore, in a preferred form of the present invention, each one ofthe anti-vibrational mounts is constituted by a laminated rubber bodyhaving a number of rubber layers laminated alternately and in parallelrelation with a number of thin steel sheet layers, an upper mountingplate securely fixed to an upper end of the laminated rubber body, and alower mounting plate securely fixed to lower end of the laminated rubberbody.

In this instance, preferably the frame and the lower mounting plate ofeach anti-vibrational mounts are securely fastened to each other by theuse of bolts, and stud bolts are fixedly provided either on the side ofthe cab or on the side of the upper mounting plate of theanti-vibrational mounts and adapted to be received in bolt holesprovided either on the side of the upper mounting plate or on the sideof the cab.

With the arrangements just described, at the time of mounting the cab onthe frame through the anti-vibrational mounts, the cab can beautomatically set in position relative to the anti-vibrational mountssimply by fastening the lower mounting plates of the anti-vibrationalmounts securely to the frame by means of bolts and inserting the studbolts, which are provided either on the side of the upper mountingplates of the anti-vibrational mounts or on the side of the cab, intobolt holes which are provided opposingly either on the side of the cabor on the side of the upper mounting plates of the anti-vibrationalmounts.

Further, in another preferred form of the present invention, the cab andthe upper mounting plate of each anti-vibrational mounts are securelyfastened to each other by the use of bolts, and stud bolts are fixedlyprovided either on the side of the frame or on the side of the lowermounting plate of the anti-vibrational mounts and adapted to be receivedin bolt holes provided either on the side of the lower mounting plate oron the side of the frame.

With the arrangements just described, at the time of mounting the cab onthe frame through the anti-vibrational mounts, each one of theanti-vibrational mounts can be automatically set in position relative tothe frame, upon inserting the stud bolts, which are provided either onthe side of the lower mounting plates of the anti-vibrational mounts oron the side of the frame, into bolt holes which are provided opposinglyeither on the side of the frame or on the side of the lower mountingplates of the anti-vibrational mounts.

In another preferred form of the present invention, stud bolts arefixedly provided in the lower mounting plate of each anti-vibrationalmounts and adapted to be received in bolt holes provided in the frame,and stud bolts are fixedly provided in the upper mounting plate of theanti-vibrational mounts and adapted to be received in bolt holesprovided on the part of the cab.

With the arrangements just described, at the time of mounting the cab onthe frame through the anti-vibrational mounts, the respective ones ofthe anti-vibrational mounts can be automatically set in positionrelative to the frame and the cab, upon inserting stud bolts, which areprovided on the lower and upper mounting plates of the anti-vibrationalmounts, into bolt holes which are provided opposingly on the side of theframe and the cab, respectively.

In still another preferred form of the present invention, the frame andthe lower mounting plate of each anti-vibrational mount are securelyfastened to each other by the use of bolts, and an intermediateconnecting plate is attached to the upper mounting plate of theanti-vibrational mount, the intermediate connecting plate having studbolts adapted to be received in bolt holes provided on the part of thecab.

With the arrangements just described, at the time of mounting the cab onthe frame through the anti-vibrational mounts, each of theanti-vibrational mounts which have the respective lower mounting platesfastened to the frame by means of bolts, can be automatically set inposition relative to the cab upon inserting the stud bolts on theintermediate connecting plate, which is attached to the upper mountingplate of each anti-vibrational mount, into bolt holes which are providedopposingly on the side of the cab. Besides, in this case, at the time ofreplacement of an anti-vibrational mount, it can be easily extracted ina horizontal direction as soon as the upper mounting plate is removedfrom the intermediate connecting plate, without being obstructed by thestud bolts.

Furthermore, in another preferred form of the present invention, the caband the upper mounting plate of each of the anti-vibrational mounts aresecurely fastened to each other by the use of bolts, and an intermediateconnecting plate is attached to the lower mounting plate of theanti-vibrational mount, the intermediate connecting plate having studbolts adapted to be received in bolt holes provided on the side of theframe.

With the arrangements just described, at the time of mounting the cab onthe frame through the anti-vibrational mounts, the anti-vibrationalmounts can be automatically set in position relative to the frame, uponinserting the stud bolts of the intermediate connecting plate, which isattached to the lower mounting plate of each anti-vibrational mounts,into bolt holes which are provided opposingly on the side of the frame.Besides, in this case, at the time of replacement of an anti-vibrationalmount, it can be easily extracted in a horizontal direction afterdetaching the lower mounting plate from the intermediate connectingplate, without being obstructed by the stud bolts.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a side view of a high mount cab type hydraulic excavatorapplying a first embodiment of the present invention;

FIG. 2 is a partly cutaway side view showing on an enlarged scale a bedframe, cab, anti-vibrational mounts and oil dampers employed in thefirst embodiment according to the invention;

FIG. 3 is a transverse sectional view of the cab anti-vibrational mountsand oil dampers, taken from the direction of arrows III—III of FIG. 2;

FIG. 4 is an schematic enlarged view of the cab, anti-vibrational mountsand oil damper shown in FIG. 2;

FIG. 5 is a sectional view on an enlarged scale of the cab,anti-vibrational mounts and stud bolts which are still in an unassembledstate;

FIG. 6 is a transverse sectional view taken from the direction of arrowsVI—VI of FIG. 4, showing the relationship of a force acting on an oildamper with its telescopic stretching and contracting velocities;

FIG. 7 is a schematic illustration explanatory of conditions of the cabwhen the bed frame is vibrated in a back and forth direction;

FIG. 8 is a partly cutaway side view of a main frame, cab andanti-vibrational mounts employed in a second embodiment according to thepresent invention;

FIG. 9 is a transverse sectional view taken from the direction of arrowsIX-IX of FIG. 8 and showing the anti-vibrational mounts and oil dampersof FIG. 8;

FIG. 10 is a sectional view on an enlarged scale of anti-vibrationalmounts and stud bolts employed in a third embodiment, showing the mountmembers and stud bolt in an unassembled state;

FIG. 11 is a sectional view on an enlarged scale of a cab,anti-vibrational mounts, an intermediate connecting plate and stud boltsemployed in a fourth embodiment of the present invention and shown in anunassembled state;

FIG. 12 is a sectional view on an enlarged scale of a cab,anti-vibrational mounts and stud bolts employed in a modification of thefirst embodiment and shown in an unassembled state;

FIG. 13 is a sectional view of on an enlarged scale of a cab,anti-vibrational mounts and stud bolts employed in another modificationof the first embodiment;

FIG. 14 is an enlarged sectional view of a cab, anti-vibrational mountsand stud bolts employed in a modification of the third embodiment andshown in an unassembled state;

FIG. 15 is a sectional view on an enlarged scale of a cab,anti-vibrational mounts and stud bolts employed in another modificationof the third embodiment and shown in an unassembled state;

FIG. 16 is a sectional view on an enlarged scale of a cab,anti-vibrational mounts and stud bolts employed in a modification of thefourth embodiment and shown in an unassembled state; and

FIG. 17 is a schematic illustration explanatory of conditions of a priorart cab in pitching movement.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereafter, with reference to FIGS. 1 through 16 of the accompanyingdrawings, the present invention is described more particularly aspreferred embodiments wherein the present invention is applied by way ofexample to a large-size hydraulic excavator which is generally referredto as “a high mount cab type hydraulic excavator”.

Referring first to FIGS. 1 to 7, there is shown a first embodiment ofthe present invention. In these figures, indicated at 1 is a crawlertype truck body and at 2 is a rotary body which is rotatably mounted onthe truck body 1. Provided on a front center portion of the rotary body2 is a loader bucket type working mechanism 3 for upward and downwardlifting movements.

Denoted at 4 is a main frame which constitutes a bottom portion of therotary body 2. This main frame 4 has a frame structure which extends ina horizontal direction, and a vertically standing bed frame 5 is set ona front left portion of the main frame. The rotary body 2 is largelyconstituted by the above-mentioned main frame 4 and bed frame 5, alongwith an operator's cab 13 which is located on the bed frame 5 as will bedescribed hereinafter, a housing 6 which is located on a rear portion ofthe bed frame 5 to accommodate a prime mover (not shown) etc., and acounterweight 7 attached to a rear portion of the main frame 4 at aposition behind the housing 6.

In this instance, as shown in FIGS. 2 to 4, the bed frame 5 isconstituted by: a box-like outer frame 8 which is enclosed by frontplate 8A, rear plate 8B and right and left side plates 8C and is open onthe top side thereof; a cab support plate 9 in the form of ahorizontally extended rectangular frame structure which is located in aninner upper portion of the outer frame 8 and provided with mount memberfixing portions 9A in its four corner portions to support the cab 13through anti-vibrational mounts 18 which will be described hereinafter;and vertically extending reinforcing members 10 which are attached tothe lower side of the mount member fixing portions 9A for the purpose ofreinforcing the cab support plate 9. By this arrangement, with highrigidity, the bed frame 5 is erected on the main frame 4.

Further, for attaching oil dampers 24 which will be describedhereinafter, four brackets 11 are securely fixed to the front and rearplates 8A and 8B of the outer frame 8 by welding or other suitablemeans, symmetrically in the back and forth and transverse directions ofthe machine. Mounting seats 12 for supporting lower ends of theanti-vibrational mounts 18 are securely welded or fixed to top surfacesof the mount member fixing portions 9A of the cab support plate 9.

Indicated at 13 is a cab which is located on the bed frame 5 to definean operating room for the operator. The cab 13 is in the form of abox-like enclosure having a top side section 13A, a front side section13B, a rear side section 13C and left and right side sections 13D (onlyone of which is shown in the drawings) and formed, for example, bywelding together thin press-formed steel plates. Further, brackets 13Efor a flooring plate are securely fixed by welding to inner lowerportions of the cab 13, and a floor panel 14 is fixedly bolted to thebrackets 13E to form a bottom of the cab 13. An operator's seat isprovided internally of the cab 13 along with control levers andinstruments (both not shown) for operating the working mechanism 3.

In this instance, at positions opposing the mounting seats 12 on thepart of the bed frame 5, four mounting seats 15 are securely welded tothe lower side of the floor panel 14 for the purpose of supporting upperends of the anti-vibrational mounts 18. In addition, in order to mountthe oil dampers 24, four brackets 16 on the side of the cab are securelyfixed to the lower side of the floor panel 14 by welding or by othersuitable means symmetrically in back and forth and transverse directionsof the machine.

Indicated at 17 are four stud bolts (only two stud bolts are shown inthe drawing) which are projected downward through the mounting seats 15on the side of the cab 13. As shown in FIG. 5, these stud bolts 17 arepassed through bolt passage holes 21A which are bored in upper mountingplates 21 of the anti-vibrational mounts 18 as will be describedhereinbelow.

Denoted at 18 are the anti-vibrational mounts which are located atpositions in four corner portions and between the floor panel 14 of thecab 13 and the bed frame 5. These anti-vibrational mounts 18 are eachconstituted by a lower mounting plate 19, an upper mounting plate andlaminated rubber body 23, which will be described hereinafter.

The lower mounting plate 19 is attached to a mounting seat 12 on theside of the bed frame 5, and constituted by a rectangular steel platewith bolt passage holes 19A bored in four corner portions thereof.Further, the lower mounting plate 19 is fastened to the mounting seat 12by a bolt 20 which is passed through the bolt passage hole 19A.

The upper mounting plate 21 is attached to a mounting seat 15 on theside of the cab 13, and similarly constituted by a rectangular steelplate with bolt passage holes 21A bored in four corner portions thereof.Further, the upper mounting plate 21 is fastened to a mounting seat 15by threading and tightening a nut 22 onto a stud bolt 17 which isprojected from the mounting seat 15 on the part of the cab 13 and passedthrough the bolt passage hole 21A.

The laminated rubber body 23 which is interposed between the upper andlower mounting plates 21 and 19, is constituted by a number of laminatedresilient rubber layers 23A, and thin steel sheet layers 23B which areinterposed alternately and parallel with the resilient rubber layers23A. The top and bottom sides of the laminated rubber body 23 aresecurely fixed to the upper and lower mounting plates 21 and 19 bywelding or by the use of an adhesive, respectively.

In this instance, the laminated rubber body 23, which is formed bylaminating a number of rubber layers 23A alternately with a number ofsteel sheet layers 23B, has relatively high rigidity against vibrationsof vertical directions, because the thin steel sheet layers 23B act toprevent flexure of the rubber layers 23A when a load is applied thereonfrom or in a vertical direction. On the other hand, the laminated rubberbody 23 has relatively low rigidity against vibrations of an horizontaldirections, because the resilient rubber layers 23A between the thinsteel sheet layers 23B are allowed to flex to a relatively large degreewhen a load is applied thereto from or in a horizontal direction, forexample, from a lateral, front or rear side of the laminated rubber body23.

Accordingly, each one of the anti-vibrational mounts 18 with thelaminated rubber body 23, functions to suppress vibrational movements ofthe cab 13 particularly in the back and forth direction (hereinafterreferred to as “pitching” for brevity), in the lateral direction(hereinafter referred to as “rolling” for brevity) and in the verticaldirection (hereinafter referred to as “bouncing” for brevity), therebysupporting the cab 13 in a quite stabilized state. Even if vibration istransmitted to the cab 13, the laminated rubber bodies 23 which haverelatively high rigidity in the vertical direction function to translatethe vibration of the cab 13 into horizontal parallel movements andprevent pitching and rolling movements of the cab 13.

Denoted at 24 are four oil dampers which function as vibrationattenuators for the cab 13. These oil dampers 24 are locatedhorizontally in four corner portions between the cab 13 and the floorpanel 14 and in corresponding positions relative to the anti-vibrationalmounts 18. In this instance, as shown in FIGS. 4 and 6, each one of theoil dampers 24 is composed of a tube 25 having a piston (not shown)slidably fitted therein, and a piston rod 26 which is connected at itsbase or inner end to the piston within the tube 25 and projected out ofthe tube 25 at the other outer end. Attenuating force is produced byeach oil damper 24 as the piston is reciprocated within the tube 25against resistance of oil. Further, a mounting eye 25A is securely fixedto the base end of the tube 25 of each oil damper, and a mounting bolt26A is securely fixed to the fore projected end of the piston rod 26.The piston rod 26 is covered with a dust cover 26B.

By way of the mounting eye 25A at the base end of the tube 25, each oildamper 24 is secured resiliently through a rubber bush 27 to a bracket11 on the side of the frame, which is securely fixed to the outer frame8 of the bed frame 5. The mounting bolt 26A at: the fore end of thepiston rod 26 is secured resiliently through a cushioning rubber member28 to a bracket 16 on the side of the cab 13, which is securely fixed tothe lower side of the floor panel 14. Consequently, the oil dampers 24are arranged to connect the bed frame 5 and the floor panel 14 of thecab 13 with each other.

In this connection, as shown particularly in FIG. 3, the longitudinalaxes O—O of the oil dampers 24 which are located in a left front portionand in a right front portion of the floor panel 14 are intersected witheach other on the front side of the floor panel 14 and with aninclination angle θ relative to back and forth direction, X—X of thefloor panel 14. On the other hand, the longitudinal axis O—O of the oildampers 24 which are located in a left rear portion and in a right rearportion of the floor panel 14 are intersected with each other on therear side of the floor panel and with an inclination angle θ relative tothe back and forth direction of the floor panel 14.

Namely, the respective oil dampers 24 are mounted in an inclined angularposture or position such that the longitudinal axes O—O of the oildampers 24 circumscribe an imaginary ellipse S (indicated by two-dotchain line in FIG. 3) which is drawn on a horizontal plane at and arounda center portion of the floor panel 14.

In this instance, the inclination angle θ of each oil damper 24 isdetermined on the basis of a ratio of attenuation force A, which isnecessary for attenuation of vibration of the cab 13 in back and forthdirections, to attenuation force B which is necessary for attenuation ofvibration in lateral directions. A method of computing the inclinationangle θ of the oil dampers 24 is described below with reference to FIG.6.

Firstly, given that V1 is the velocity of movement of the cab 13 when invibration in a back and forth direction, the velocity V1′ of telescopicmovement of the oil damper 24 is expressed by following Equation 1.

 V1′=V1 cos θ  [Equation 1]

Nextly, given that V2 is the velocity of movement of the cab 13 when invibration in a lateral direction, the velocity V2′ of telescopicmovement of the oil damper 24 is expressed by following Equation 2.

V2′=V2 sin θ  [Equation 2]

Thus, if the attenuation coefficient of the oil damper 24 is C, theattenuation force F in the axial direction of the oil damper 24 isexpressed by following Equation 3.

F=C(V1′+V2′)=C(V1 cos θ+V2 sin θ)  [Equation 3]

Further, a component F1 in a back and forth direction of the attenuationforce F is expressed by following Equation 4.

F1=F cos θ  [Equation 4]

Similarly, a component F2 in a lateral direction of the attenuationforce F is expressed by following Equation 5.

F2=F sin θ  [Equation 5]

Thus, a component C1 in a back and forth direction of the attenuationcoefficient C is expressed by following Equation 6.

C1=F1/V1=F cos θ/V1=C cos θ(V1 cos θ+V2 sin θ)/V1  [Equation 6]

On the other hand, a component C2 in a lateral direction of theattenuation coefficient C is expressed by following Equation 7.

C2=F2/V2=F sin θ/V2=C sin θ(V1 cos θ+V2 sin θ)/V2  [Equation 7]

In this instance, of the four oil dampers 24, one of the two oil damperswhich form one pair in a lateral or transverse direction has aninclination angle θ of a positive value in a horizontal plane while theother oil damper 24 has an inclination angle θ of a negative value.Accordingly, a total attenuation coefficient C1t in the back and forthdirection, which is a sum of attenuation coefficients C1 of the four oildampers in the back and forth direction, is expressed by followingEquation 8. $\begin{matrix}\begin{matrix}{{C1t} = \quad {\frac{2C\quad \cos \quad {\theta \left( {{{V1}\quad \cos \quad \theta} + {{V2}\quad \sin \quad \theta}} \right)}}{V1} +}} \\{\quad \frac{2C\quad {\cos \left( {- \theta} \right)}\left\{ {{{V1}\quad {\cos \left( {- \theta} \right)}} + {{V2}\quad \sin \quad \left( {- \theta} \right)}} \right\}}{V1}} \\{= \quad {4C\quad \cos^{2}\theta}}\end{matrix} & \left\lbrack {{Equation}\quad 8} \right\rbrack\end{matrix}$

Similarly, a total attenuation coefficient C2t in a lateral direction,which is a sum of attenuation coefficients C2 of the four oil dampers inthe lateral direction, is expressed by following Equation 9.

C2t=4C sin²θ  [Equation 9]

In this case, a ratio of attenuation force A which is necessary forattenuation of vibration of the cab 13 in the back and forth direction,to attenuation force B which is necessary for attenuation of vibrationin the lateral direction, can be expressed as a ratio of the totalattenuation coefficient C1t in the back and forth direction to the totalattenuation coefficient C2t in the lateral direction, as in followingEquation 10.

 C1t:C2t=A:B  [Equation 10]

Hence, from Equations 8 to 10, Equation 11 follows.

4C sin²θ×A=4C cos²θ×B  [Equation 11]

Accordingly, Equation 12 is obtained.

(1−cos²θ)×A=cos²×B  [Equation 12]

Thus, the inclination angle θ of the respective oil dampers 24 can beexpressed by way of the attenuation force A necessary for attenuation ofvibration of the cab 13 in the back and forth direction and theattenuation force B necessary for attenuation of vibration in thelateral direction, as in Equation 13.

θ=cos⁻¹{square root over (A/(A+B))}  [Equation 13]

In this manner, the inclination angle θ of the oil dampers 24 isdetermined according to the attenuation force A which is necessary forattenuation of vibrations of the cab 13 in a back and forth directionand the attenuation force B which is necessary for attenuation ofvibrations in a lateral direction.

Accordingly, adjustments are made to the inclination angle θ for eachone of the oil dampers 24 which are each set in a horizontal position.With this oil damper arrangement, it becomes possible to attenuatevibrations of the cab 13 occurring in back and forth directions as wellas vibrations occurring in lateral directions through the respective oildampers 24. This means that there is no necessity for using two types ofoil dampers, for example, one for attenuation of vibrations of the cab13 in the back and forth direction and the other for attenuation ofvibrations in the lateral direction, and it becomes possible to simplifythe administration of inventory and to cut costs. Besides, in case thecab 13 is put in vibration in the rotational direction (hereinafterreferred to as “yawing” for brevity), such yawing movements can also beattenuated by the oil dampers 24.

The hydraulic excavator, with the above-described arrangements accordingto the present embodiment, can effectively damp vibrations of the cab 13which is mounted on the hydraulic excavator, in the manner as describedbelow.

Firstly, for example, if the main frame 4 is largely vibrated back andforth while the truck body 1 is in travel or during a ground excavatingoperation by the working mechanism 3, upper portions of the bed frame 5are also vibrated largely in the back and force direction, and thevibration of the bed frame 5 is transmitted to the respectiveanti-vibrational mounts 18, thereby causing lower portions of thelaminated rubber bodies 23 to vibrate likewise in the back and forthdirection. However, since the laminated rubber bodies 23 of theanti-vibrational mounts 18 have relatively low rigidity againstvibrations of horizontal directions, they are caused to flex in the backand forth direction between the bed frame 5 and the floor panel 14 ofthe cab 13. Therefore, even if the bed frame 5 is vibrated largely inthe back and forth direction as shown in FIG. 7, the oil dampers 24 actto prevent direct transmission of the vibration to the cab 13 and tosuppress vibrations of the cab 13.

In addition, even if back and forth vibrations are transmitted to thecab 13, the laminated rubber bodies of the anti-vibrational mounts 18which have high rigidity against vibrations in vertical directionsfunction to translate the vibrations into horizontal parallel movements.Therefore, the cab 13 is prevented from being largely shaken by pitchingto ensure improved amenity within the cab 13 as well as improvedmaneuverability of control levers.

Further, even in case the main frame 4 is vibrated to the right and leftor in lateral directions, thereby causing upper portions of the bedframe 5 to likewise vibrate largely in lateral directions, the laminatedrubber bodies 23 of the anti-vibrational mounts 18 are flexed betweenthe bed frame 4 and the floor panel 14 of the cab 13, thereby to preventdirect transmission of vibration from the bed frame 5 to the cab 13 andto suppress vibrational movements of the cab 13.

Therefore, even if vibrations of lateral directions were transmitted tothe cab 13, the laminated rubber bodies 23 of the anti-vibrationalmounts 18 which have relatively high rigidity in the vertical directionfunction to translate the vibrations into horizontal parallel movementsof the cab 13. Therefore, the cab 13 is prevented from being shakenlargely by rolling vibrations to ensure improved amenity within the cab13.

Further, the laminated rubber bodies 23 of the anti-vibrational mounts18 which have high rigidity in the vertical direction function toprevent inclinations of the cab 13 on the bed frame 5 even when thevehicle body is inclined on a slope, for example, always maintaining thecab 13 in a horizontal state relative to the bed frame 5.

On the other hand, in case the laminated rubber bodies 23 of theanti-vibrational mounts 18 are flexed due to vibration of the bed frame5 to put the cab 13 in horizontal parallel movements, the restoringforces of the laminated bodies 23 may give rise to residual vibrationsof the cab 13 in horizontal directions. However, by the oil dampers 24which are mounted horizontally between the bed frame 5 and the floorpanel 14 of the cab 13, such residual vibrations can be attenuated to asufficient degree for preventing the phenomenon of resonance which mightotherwise be caused is by residual vibrations.

In this regard, each one of the oil dampers 24 is mounted in ahorizontal plane and in an inclined posture at a certain inclinationangle θ from the back and forth directions of the cab 13. Therefore,despite the use of oil dampers 24 of the same type, adjustments can bemade of the attenuation force against residual vibrations in the backand forth directions of the cab 13 as well as of the attenuation forceagainst residual vibrations in lateral directions, by suitably varyingthe inclination angle θ.

It follows that there is no necessity for employing two types of oildampers, one type for attenuation of vibrations of the cab 13 in backand forth directions and another type for attenuation of vibrations ofthe cab 13 in lateral directions. Therefore, the above-describedarrangements according to the present embodiment contribute to simplifythe administration of inventory to a significant degree and to realizecost reductions.

Further, for example, when the cab 13 is put in yawing movements as aresult of rotational movements of the upper rotary body 2, such yawingmovements can also be attenuated by the respective oil dampers 24.

Thus, according to the present embodiment, the anti-vibrational mounts18 which support the cab 13 on the bed frame 5 are each constituted bythe laminated rubber body 23 which is arranged to have high rigidityagainst vibrations in vertical directions but to have low rigidityagainst vibrations in lateral directions. These characteristics of thelaminated rubber bodies 23 prevent the cab 13 from being shaken to aconsiderable degree by pitching and rolling vibrations, and contributeto improve the amenity of the operator's cab 13 as well as themaneuverability of control levers or other instruments in the cab 13.

In addition, for attenuating vibrations of the cab 13, the oil dampers24 are provided in the four corner portions between the bed frame 5 andthe floor panel 14 of the cab 13. Therefore, even if residual vibrationsoccur to the cab 13 under the influence of restoring forces of thelaminated rubber bodies 23 which constitute the anti-vibrational mounts18, such residual vibrations can also be attenuated by the oil dampers24. The oil dampers 24 thus prevent the phenomenon of resonance whichmight otherwise occur to the cab 13 under the influence of residualvibrations, thereby improving the amenity of the cab 13 all the more.

The present embodiment is particularly arranged to facilitate the job ofassembling the cab 13 on the bed frame 5 through the anti-vibrationalmounts 18, as described below with reference to FIG. 5.

In the first place, the lower mounting plates 19 of the anti-vibrationalmounts 18 are fastened by bolts 20 to the mounting seats 12 which aresecurely fixed on the upper side of the cab support plate 9. Then, thecab 13 is lifted up by the use of a crane or the like (not shown) to aposition where the mounting seats 15 on the lower side of the floorpanel 14 of the cab 13 face the corresponding upper mounting plates 21of the anti-vibrational mounts 18.

Next, the cab 13 is lowered until the mounting seats 15 on the side ofthe cab 13 come into abutting engagement with the upper mounting plates21 of the anti-vibrational mounts 18. At this time, the stud bolt 17which is projected downward from each mounting seat 15 can be easilythreaded into the bolt hole 21A of the opposing upper mounting plate 21when the cab 13 is lowered toward the anti-vibrational mounts 18.

Then, the nuts 22 are threaded onto the stud bolts 17 which areprojected downward on the lower side of the upper mounting plates 21through the bolt holes 21A, thereby fastening the upper mounting plates21 of the respective anti-vibrational mounts 18 to the floor panel 14 ofthe cab 13. As a result, the cab 13 is mounted on the cab support plate9 of the bed frame 5 through the anti-vibrational mounts 18.

In this instance, as the cab 13 is lowered onto the anti-vibrationalmounts 18 on the part of the bed frame 5, the cab 13 is automaticallybrought into a correct position relative to the anti-vibrational mounts18 upon passing the stud bolts 17 on the lower side of the floor panel14 of the cab 13 through the bolt holes 21A in the upper mounting plates21 of the anti-vibrational mounts 18.

Therefore, the cab 13 can be assembled and mounted in position quiteeasily and efficiently, freeing the workers from a danger of getting afinger or fingers pinched between the cab and an anti-vibrational mount,as often experienced, for example, in the case of the prior art in whichrequires the insertion of fastening bolts into bolt holes while holdingbolt holes on the side of a cab, which is lifted up by a crane, inmatching positions relative to bolt holes on the side of theanti-vibrational mounts.

Turning now to FIGS. 8 and 9, there is shown a second embodiment of thepresent invention, which is characterized in that, directly through theanti-vibrational mounts, the cab is supported on a main frame whichconstitutes a bottom portion of a rotary body to provide an ordinarytype hydraulic excavator instead of a high mount type. In the followingdescription of the second embodiment, those component parts which arecommon with the foregoing first embodiment are simply designated bycommon reference numerals or characters to avoid repetitions of the sameexplanations.

In the figures, indicated at 31 is a main frame which is employed in ahydraulic excavator of the present embodiment. The main frame 31includes a center frame 32 which is mounted on a rotational mechanism(not shown), and, in place of the bed frame 5 of the foregoing firstembodiment, a cab support structure 33 is provided on a left frontportion of center frame 32.

In this instance, the center frame 32 is constituted by thick steelplates, including a bottom plate 32A and a pair of vertical or upright32B (only one vertical plate is shown in the drawing) plates which areextended on and along the bottom plate 32A in the back and forthdirection of the machine. The cab support structure 33 is largelyconstituted by a cross beam 33A of U-shape in section which is extendedtransversely across a front portion of the center frame 32, a rear frame33B of L-shape in section which is extended in the transverse directionon the rear side of the center frame 32, a side frame 33C which isextended in the back and forth directions and securely connected to leftends of the cross beam 33A and rear frame 33B, a longitudinal beam 33Dwhich is extended in the longitudinal direction from a right end of thecross beam 33A in parallel relation with the side frame 33C, and a frontframe 33E of L-shape in section which is extended in the transversedirection and arranged to connect front ends of the side frame 33C andlongitudinal beam 33D with each other.

Four seat members 34 each of L-shape in section are securely fixed tothe rear frame 33B and front frame 33E of the cab support structure 33.An anti-vibrational mount 18 is mounted between each seat member 34 andthe floor panel 14 of the cab 13 to support the cab 13 resiliently onthe main frame 31.

Further, on the side of the frame, four brackets 11 in total aresecurely fixed to the rear and front frames 33B and 33E of the cabsupport structure 33, for example, by welding in symmetrical positionsin the back and forth and transverse directions. In this case, oildampers 24 are mounted in positions between these brackets 11 on theside of the frame and four brackets 16 which are securely fixed to thelower side of the floor panel 14 of the cab 13, so that the main frame31 and the floor panel 14 of the cab 13 are connected with each otherthrough the oil dampers 24.

The oil dampers 24 of this embodiment are similarly arranged in angularpositions. Namely, the oil dampers 24 in a left front portion and in aright front portion of the cab 13 are arranged in such angular positionsthat their longitudinal axes O—O are intersected with each other on thefront side of the cab 13 with an inclination angle θ from the back andforth direction X—X. On the other hand, the oil dampers 24 in a leftrear portion and in a rear right portion of the cab 13 are arranged insuch angular positions that their longitudinal axis O—O are intersectedwith each other on the rear side of the cab 13 with an inclination angleθ from the back and forth direction X—X.

In the case of the hydraulic excavator of the present embodiment,employing the above-described arrangements, when the main frame 31 isput in vibration in the back and forth directions or in a lateraldirection (or in a horizontal direction), the laminated rubber bodies 23of the anti-vibrational mounts 18 are caused to flex between the mainframe 31 and the floor panel 14 of the cab 13 to prevent directtransmission of the vibration from the main frame 31 to the cab 13,thereby suppressing vibrations of the cab 13.

Besides, since the laminated rubber bodies 23 of the anti-vibrationalmounts 18 are arranged to have high rigidity against vibrations in thevertical direction, the cab 13 is put in horizontal parallel movements.Therefore, the anti-vibrational mounts prevent the cab 13 from beinglargely shaken by pitching or rolling vibrations, thereby improving theamenity of the cab 13 as well as the maneuverability of control leverswithin the cab 13.

In addition, when the cab 13 is put in horizontal parallel movements asa result of vibration of the main frame 31, the residual horizontalvibrations which may occur on the cab 13 due to restoring forces of thelaminated rubber bodies 23, can be attenuated by the oil dampers 24which are interposed between the main frame 31 and the floor panel 14 ofthe cab 13 to preclude the phenomenon of resonance which might occur asa result of the residual vibrations.

Now, referring to FIG. 10, there is shown a third embodiment of thepresent invention, which is characterized in that the stud bolts whichfasten the anti-vibrational mounts to the cab are provided on the partof the upper mounting plates of the anti-vibrational mounts. In thefollowing description of the third embodiment, those component partswhich are common with the foregoing first embodiment are simplydesignated by common reference numerals or characters to avoidrepetitions of same explanations.

In that figure, indicated at 41 is a floor panel of the cab 13, which isbored with a plural number of bolt holes 41A (only two of which areshown in the drawing) to receive stud bolts which are provided on thepart of the anti-vibrational mounts 18 as will be described hereinbelow.

Denoted at 42 are mounting seat plate which are securely fixed to thelower side of the floor panel 41. Each mounting seat plate 42 is boredwith four bolt holes 42A in axially aligned relation with the bolt holes41A in the floor panel 41.

Indicated at 43 are two of four stud bolts which are, securely fixed tothe upper mounting plates 21 of the anti-vibrational mounts 18. Each oneof these stud bolts 43 is planted in an upright position and adapted tobe passed through the bolt hole 42A in the mounting seat plate 42 andthe bolt hole 41A in the floor panel 41.

In the case of the present embodiment with the arrangements justdescribed, the cab 13 is mounted on the cab support plate 9 through theanti-vibrational mounts 18 in the manner as follows. In the first place,the lower mounting plates 19 of the anti-vibrational mounts 18 arefastened to the mounting seat 12 of the cab support plate 9 by the useof bolts 20, and then the cab 13 is lifted up by the use of a crane orthe like (not shown) to bring the mounting seat plates 42 on the lowerside of the floor panel 41 into face to face relation with the uppermounting plates 21 of the anti-vibrational mounts 18.

In the next place, the cab 13 is lowered to receive the stud bolts 43 onthe anti-vibrational mounts 18 in the bolt holes 42A and 41A in themounting seat plates 42 and the floor panel 41, respectively, and thecab 13 is fixed on the cab support plate 9 through the anti-vibrationalmounts 18 by threading and tightening the nuts 44 onto the upper ends ofthe stud bolts 43 which are projected on the upper side of the floorpanel 41 through the bolt holes 41A.

Thus, according to the present embodiment, as the cab 13 is lowered ontothe anti-vibrational mounts 18, it can be automatically set in apredetermined position relative to the anti-vibrational mounts 18 in asafe and facilitated manner upon inserting the stud bolts 43 into thebolt holes 41A and 42A in the floor panel 41 and the mounting seatplates 42.

Referring now to FIG. 11, there is shown a fourth embodiment of thepresent invention, which is characterized in that an intermediateconnecting plate with stud bolts is attached to the upper mounting plateof the anti-vibrational mount. In the following description of thefourth embodiment, those component parts which are common with theforegoing first embodiment are designated by common reference numeralsor characters to avoid repetitions of same explanations.

Indicated at 51 in that figure is a floor panel of the cab 13. Opened inthe floor panel 51 are a number of bolt holes 51A (only two of which areshown in the drawing) for receiving stud bolts 54, which will bedescribed hereinafter.

Designated at 52 is an intermediate connecting plate which is fixed tothe top side of the upper mounting plate 21 of the anti-vibrationalmount 18 by means of four bolts 53 (only two of which are shown in thedrawing). Four upright stud bolts 54 (only two of which are shown in thedrawing) are planted in the intermediate connecting plate 52. These studbolts 54 are projected upward through the bolt holes 51A in the floorpanel 51 of the cab.

According to the present embodiment with the arrangements Justdescribed, at the time of mounting the cab 13 on the cab support plate 9through the anti-vibrational mounts 18 which are each provided with theintermediate connecting plate 52, in the first place the intermediateconnecting plate 52 is attached to the upper mounting plate 21 of eachanti-vibrational mount 18 by means of the bolts 53, and the lowermounting plate 19 of each anti-vibrational mount 18 is fastened to themounting seat 12 of the cab support plate 9 by means of the bolts 20.

In the next place, the cab 13 is lowered by the use of a crane or thelike (not shown) to receive the stud bolts 54 of the respectiveintermediate connecting plates 52 in the bolt holes 51A in the floorpanel 51 of the cab 13, and the nuts 55 are threaded and tightened ontothe upper ends of the stud bolts 54 which are respectively projected onthe upper side of the floor panel 51 through the bolt holes 51A. As aresult, the cab 13 is mounted on the cab support plate 9 through theanti-vibrational mounts 18.

Thus, according to the present embodiment, as the cab 13 is lowered ontothe anti-vibrational mounts 18, it can also be automatically broughtinto a predetermined position relative to the anti-vibrational mounts 18in a safe and facilitated manner upon inserting the stud bolts 54 of theintermediate connecting plates 52 into the bolt holes 51A in the floorpanel 51 of the cab 13.

Further, according to the present embodiment, for example, when one ofthe anti-vibrational mounts 18 is damaged and should be removed forreplacement, it can be extracted easily in a horizontal direction afterremoving the bolts 20 and 53 from the lower and upper mounting plates 19and 21 of the anti-vibrational mount 18. Therefore, a damagedanti-vibrational mount can be replaced quite easily, without entailingany troublesome job, for example, a job of lifting up the cab 13 forextracting the stud bolts 54 out of the bolt holes 51A of the floorpanel 51.

In the above-described first embodiment, the stud bolts 17 are shown asbeing provided on the mounting seats 15 which are securely fixed on thelower side of the floor panel 14 of the cab 13. However, it is to beunderstood that the present invention is not restricted to thisparticular arrangement. For instance, as in a modification shown in FIG.12, arrangements may be made to insert bolts 61 downward from the upperside of the floor panel 14 and through the mounting seat 15 and to useas stud bolts the lower end portions of the bolts 61 which are projecteddownward on the lower side of the mounting seat 15.

Further, in the above-described first embodiment, the stud bolts 17 areshown by way of example as being provided on the mounting seat 15 whichis securely fixed to the lower side of the floor panel 14. However, thepresent invention is not restricted to this particular arrangement. Forinstance, in the manner as in another modification shown in FIG. 13, thestud bolts 17 may be fixedly planted in the mounting seat 12 which isfixed on the upper side of the cab support plate 9. Alternatively, thestud bolts 17 may be provided on each one of the mounting seats 12 and15 if desired.

Further, in the above-described third embodiment, the stud bolts 43 areshown by way of example as being fixedly planted in the upper mountingplate 21 of the anti-vibrational mount 18. However, the presentinvention is not restricted to this particular arrangement. Forinstance, as in a modification shown in FIG. 14, the stud bolts 43 maybe fixed in the lower mounting plate 19 of the anti-vibrational mount 18if desired. Alternatively, as in another modification shown in FIG. 15,the stud bolts 43 may be fixed in the upper and lower mounting plates 18and 19 of the anti-vibrational mount 18 if desired.

Moreover, in the above-described fourth embodiment, the intermediateconnecting plate 52 is shown by way of example as being attached to theupper mounting plate 21 of the anti-vibrational mount 18. However, thepresent invention is not restricted to this particular arrangement. Forinstance, as in a modification shown in FIG. 16, there may be employedan arrangement in which the intermediate connecting plate 52 is attachedto the lower mounting plate 19 of the anti-vibrational mount 18, withthe stud bolts 54 of the intermediate connecting plate 52 passed throughthe bolt holes 9B which are provided in the cab support plate 9.

Furthermore, in the foregoing embodiments, by way of example, thepresent invention has been described in connection with a particulartype of construction machine. However, the present invention is notrestricted to the particular type shown, and can be similarly applied toother construction machines such as wheel loaders, hydraulic cranes andthe like.

INDUSTRIAL APPLICABILITY

As clear from the foregoing particular description, according to thepresent invention, each one of anti-vibrational mounts which areprovided between a frame and cab, is constituted by a laminated rubberbody which is arranged to have high rigidity against vibrations invertical directions and low rigidity against vibrations in horizontaldirections. Therefore, when the frame is put in vibration in ahorizontal direction, the laminated rubber bodies of theanti-vibrational mounts are caused to flex in a horizontal directionbetween the frame and cab, thereby preventing direct transmission of thevibration from the frame to the cab and suppressing vibration of thecab.

Besides, even if the vibration of the frame is transmitted to the cab,the cab is simply put in horizontal parallel movements and preventedfrom being shaken largely by pitching or rolling because the laminatedrubber bodies have high rigidity against vibrations in verticaldirections as mentioned hereinbefore, contributing to improve theamenity in the cab as well as the maneuverability of control levers inthe cab.

Further, according to the present invention, four vibration attenuatingdevices are provided in four corner portions between the frame and thecab and in cooperative positions relative to the anti-vibrationalmounts. Therefore, when the cab is put in horizontal parallel movementsas a result of vibration of the frame, the vibration attenuating devicesact to effectively attenuate residual vibrations which might occur tothe cab due to restoring forces of the laminated rubber bodies of theanti-vibrational mounts, thus contributing to improve the amenity withinthe cab all the more.

In this instance, according to the present invention, two of the fourvibration attenuating devices, which are located in front portions ofthe cab, are mounted in a horizontal plane in an angular posture suchthat respective longitudinal axes are intersected with each other on thefront side of the cab, while the remaining two vibration attenuatingdevices are mounted in a horizontal plane and in an angular posture suchthat respective longitudinal axes are intersected with each other on therear side of the cab. Therefore, the vibration attenuating devices canproduce attenuating forces effectively against vibrations in back andforth directions of the cab and also against vibrations in lateraldirections.

In the case of the above-described arrangements according to the presentinvention, there is no need for using two types of oil dampers, one forattenuating vibrations in back and forth directions of the cab and theother for attenuating vibrations in lateral directions, whichcontributes to simplify the administration of the inventory and to cutcosts to a significant degree. Furthermore, even if yawing occurs to thecab as a result of a rotating operation, such yawing movements can alsobe attenuated effectively by the vibration attenuating devices.

What is claimed is:
 1. A construction machine having a support frame, anoperator's cab mounted on said frame and internally defining anoperating room, and four anti-vibrational mounts located in four cornerportions between said frame and cab to support the cab on the frame in avibration damped state, wherein: each of said anti-vibrational mountscomprises a laminated rubber body having relatively high rigidityagainst vibration in a vertical direction and relatively low rigidityagainst vibration in a horizontal direction; and wherein saidconstruction machine further comprises four vibration attenuatingdevices located in said four corner said construction machine furthercomprises four vibration attenuating devices located in said four cornerportions between said frame and cab and in cooperative positionsrelative to said anti-vibrational mounts to attenuate horizontalvibrations transmitted to said cab.
 2. A construction machine as definedin claim 1, wherein said frame is a main frame constituting a bottomportion of a rotary body of said machine, and said cab is supported onsaid main frame through said anti-vibrational mounts.
 3. A constructionmachine as defined in claim 1, wherein said frame is composed of a mainframe constituting a bottom portion of a rotary body of said machine anda bed frame mounted vertically on said main frame, and said cab issupported on said bed frame through said anti-vibrational mounts.
 4. Aconstruction machine as defined in claim 1, wherein each said laminatedrubber body has a number of rubber layers laminated alternatively and inparallel relation with a number of thin steel sheet layers, and whereinan upper mounting plate is securely fixed to an upper end of each saidlaminated rubber body, and a lower mounting plate securely fixed to alower end of each said laminated rubber body.
 5. A construction machineas defined in claim 4, wherein said frame and said lower mounting plateof each said anti-vibrational mount are securely fastened to each otherby bolts, and stud bolts are fixedly provided either on a side of saidcab or on a side of said upper mounting plate of said anti-vibrationalmounts and adapted to be received in bolt holes provided either on theside of said upper mounting plate or on the side of said cab.
 6. Aconstruction machine as defined in claim 4, wherein said cab and saidupper mounting plate of each said anti-vibrational mount are securelyfastened to each other by bolts, and stud bolts are fixedly providedeither on a side of said frame or on a side of said lower mounting plateof said anti-vibrational mounts and adapted to be received in bolt holesprovided either on the side of said lower mounting plate or on the sideof said frame.
 7. A construction machine as defined in claim 4, whereinstud bolts are fixedly provided in said lower mounting plate of eachsaid anti-vibrational mount and adapted to be received in bolt holesprovided in said frame, and stud bolts are fixedly provided in saidupper mounting plate of each said anti-vibrational mount and adapted tobe received in bolt holes provided on said cab.
 8. A constructionmachine as defined in claim 4, wherein said frame and said lowermounting plate of each said anti-vibrational mount are securely fastenedto each other by bolts, and an intermediate connecting plate is attachedto said intermediate connecting plate having stud bolts adapted to bereceived in bolt holes provided on said cab.
 9. A construction machineas defined in claim 4, wherein said cab and said upper mounting plate ofeach said anti-vibrational mount are securely fastened to each other bybolts, and an intermediate connecting plate is attached to said lowermounting plate of each said anti-vibrational mount, said intermediateconnecting plate having stud bolts adapted to be received in bolt holesprovided on said frame.
 10. A construction machine having a supportframe, an operator's cab mounted on said frame and internally definingan operating room, and four anti-vibrational mounts located in fourcorner portions between said frame and cab to support the cab on theframe in a vibration damped state, wherein: each of saidanti-vibrational mounts comprises a laminated rubber body havingrelatively high rigidity against vibration in a vertical direction andrelatively low rigidity against vibration in a horizontal direction;said construction machine further comprising four vibration attenuatingdevices located in said four corner portions between said frame and caband in cooperative positions relative to said anti-vibrational mounts toattenuate horizontal vibrations transmitted to said cab; and wherein twoof said vibration attenuating devices are located in front portions ofsaid cab and are mounted in a horizontal plane and in an angular posturesuch that respective longitudinal axes of said two of said vibrationattenuating devices are intersected with each other on a front side ofsaid cab, and another two of said vibration attenuating devices arelocated in rear portions of said cab and are mounted in said horizontalplane and in an angular posture such that respective longitudinal axesof said another two of said vibration attenuating devices areintersected with each other on a rear side of said cab.
 11. Aconstruction machine having a support frame, an operator's cab mountedon said frame and internally defining an operating room, and fouranti-vibrational mounts located in four corner portions between saidframe and cab to support the cab on the frame in a vibration dampedstate, wherein: each of said anti-vibrational mounts comprises alaminated rubber body having relatively high rigidity against vibrationin a vertical direction and relatively low rigidity against vibration ina horizontal direction; and wherein said construction machine furthercomprises four vibration attenuating devices located in said four cornerportions between said frame and cab and in cooperative positionsrelative to said anti-vibrational mounts to attenuate horizontalvibrations transmitted to said cab, each of said vibration attenuatingdevices having a longitudinal axis thereof located in a circumscribingposition relative to an imaginary ellipse drawn around a bottom centerportion of said cab.